In fourth grade, your child will use the metric system to measure length, mass, and capacity. Length refers to the measurement of something from end to end. Long lengths are called distance. 

Mass refers to the measure of the amount of matter in an object. 

Capacity refers to the maximum amount that something can contain, commonly called volume. This cup has a maximum capacity that is much smaller than the capacity of this swimming pool. 

Kilometer, meter, and centimeter are metric measurements of length. Kilogram and gram are used to measure mass. Liter and milliliter measure capacity. 

Learning what unit is appropriate for each measurement can be challenging. Ask your child: 
What unit is best to measure our trip to grandma’s house? Is it best to measure your mass in kilograms or grams? What unit is used to tell us the capacity of this juice bottle?

Talk about these units at home so your child will be confident when converting units of measure. That is, expressing a measurement in a different unit. He will recognize patterns of converting units on the place value chart. Just as one-thousand grams is equal to one kilogram, one-thousand ones is equal to one thousand. 

Your child will practice this by completing conversion charts. He will convert between units using his place value knowledge. Talking about length, mass, and capacity will help your child become familiar and confident with all types of units!

Knowing which unit is larger or smaller is important as he converts from one unit to another unit within a system of measurement. Having a strong understanding of units is very helpful when your child begins to add, subtract, multiply, and divide with units of measure.